亚高山粗枝云杉人工林对冬季降雪过程中4种金属养分元素的截留效应

Interception of Four Metal Nutrient Elements within Snowfall in a Subalpine Spruce Plantation

【目的】降雪过程中金属养分元素的输入是高海拔森林生态系统物质迁移的重要形式之一,为进一步认识亚高山金属元素的源、汇过程并且提供理论依据。【方法】以林冠层相对均一的典型川西亚高山粗枝云杉人工林为研究对象,于2015年11月至2016年4月,调查了林冠层对降雪及其K、Ca、Na和Mg 4种金属元素的截留特征。【结果】研究期间降雪量为138.56 mm,截留率为32.22%。在整个观测期内,降雪初期(11月)林冠均对降雪过程中4种金属元素具有明显的吸收作用,在这之后林冠对Mg元素表现出持续的淋溶特征。而降雪末期(3～4月)林冠层对Na和Ca和元素均表现出较强的吸收作用。K、Ca、Na和Mg 4种金属元素通过降雪输入到无林地的总量分别为:(1.93±0.35)、(6.79±0.79)、(1.94±0.32)和(0.45±0.14)kg/hm^2;林冠层对冬季降雪中4种元素的总截留量分别为:(-0.38±0.01)、(0.37±0.04)、(-0.11±0.02)和(-0.43±0.01)kg/hm^2,截留率分别为(-19.47±0.37)%、(5.49±1.21)%、(-5.74±0.36)%和(-95.46±0.50)%。【结论】粗枝云杉人工林林冠对降雪中Ca元素具有明显的吸收作用,而对林冠层的K、Mg和Na元素具有显著的淋溶作用。

[Objective] The input of metal nutrient elements within snowfall is one of important forms of material transport processes in high-altitude forest ecosystems. Understanding nutrient input within winter snowfall could provide basic theoretical support for more accurate estimates of source and sink of metal elements in subalpine area. [Method] A typical subalpine spruce plantation was selected to investigate the effects of canopy interception on metal elements of K, Ca, Na, and Mg during snowfall from November 2015 to April 2016. [Result] The total snowfall was 138.56 mm during the experimental period and the canopy interception rate was 32.22%. Forest canopy had obvious uptake effect for the four metal elements in the early snowfall （November） period, but showed continuous Mg leaching in the following period. However, the canopy has strong uptake effect on Na and Ca in the end of snowfall（March-April） period, respectively. The total input of K, Ca, Na and Mg was（1.93±0.35）, （6.79±0.79）, （1.94±0.32） and （0.45±0.14） kg/hm2 in tion of K,ea,Na and Mg was （-0.38±0.01）, （0.37±0.04）, the open area, respectively. The canopy intercep （-0.11±0.02） and （-0.43±0.01） kg/hm2,respectively.Moreover,the interception loss rate of K,Ca,Na and Mg was （-19.47±0.37）%, （5.49±1.21）%, （-5.78± 0.36）% and （-95.46±0.50）%, respectively. [Conclusion] These results reveal that subalpine spruce plantation had significant uptake effect on Ca, but had significant leaching effect on K, Mg and Na during winter snowfall.